When you are welding stainless steel, some of the common issues to arise are warped metal and charcoal-colored welds. Although it contains similar elements like carbon steel, stainless steel has the addition of alloying elements like molybdenum and chromium. This combination presents a whole new set of challenges when you are trying to weld two or more pieces of stainless steel compared to carbon steel.
You have to ensure that the oxygen that surrounds the molten pool of stainless steel is maintained at a minimum. The weld pool is going to behave differently than aluminum or carbon steel. Heat input and distortion is a major issue due to the thermal conductivity of stainless steel, which is quite less.
Although there are many things you need to bear in mind while welding stainless steel, the most important consideration is which welding process to use.
Here are some of the choices of welding processes for stainless steel:
Metal Inert Gas (MIG) or Gas Metal Arc Welding (GMAW)
MIG or GMAW as we know it is one of the more popular methods to weld stainless steel. MIG welding stainless steel and welding carbon steel share many similarities. But the shielding gas compositions are different usually. Lower amounts of oxygen are allowed while welding stainless steel so you must keep the O2 and CO2 levels at 2% or lower.
Since you would need corrosion resistance in the weld as well as the base material, you should use stainless steel welding wire. Also, see that to prevent cracking, the filler wire or base stainless steel should have a low carbon version. Or, they should have stabilizers in them. Pulsed welding waveform could help users MIG weld stainless steel more successfully.
Tungsten Inert Gas (TIG) Welding or Gas Tungsten Arc Welding (GTAW)
TIG welding is another process that is used to weld stainless steel. The process to weld carbon steel and when it is used to weld stainless steel bear resemblance. Usually, about 100% argon or helium gas is used in the process.
TIG welding requires stainless steel filler metal to keep the weld away from corrosion. Stabilized grades of stainless steel or low carbon are great as filler metals. The base metals should be stabilized or low carbon. A frequent problem with welding stainless steel is distortion. So, heat inputs should be low and travel speeds a bit fast during TIG welding stainless steel.
Flux-Cored Arc Welding
Usually, welding processes that use flu are not ideal for welding stainless steel. You can weld stainless steel with the flux-cored process. You have to use special gas mixtures. Gas-shielded flux-cored arc welding is usually a better choice to weld stainless steel than flux-cored arc welding. The reason behind this is that because it depends less on flux to protect the weld metal from the atmosphere.
Metal-Cored Arc Welding
Metal-cored arc welding is another good option for welding stainless steel. Metal-cored arc welding does not rely on flux. The metal core of the filler material is packed with powdered metals to increase the deposition.
With proper shielding gas and a wire feeding system, you can use a metal-cored arc welding for high-quality welds on stainless steel. For most of the process, a spray-transfer arc or pulsed waveform is required to make an excellent high-quality stainless steel weld with metal-cored arc welding.
Laser Beam Welding (LBW)
Laser beam welding is a common process that is used to fuse stainless steel at fast speeds and low heat inputs. You have to take care to avoid permeability and then cracking when you weld with lasers. Cracks and porosity can be prevented via lessening the amount of oxygen through shielding gas and weld parameter optimization.
You can never perform laser beam welding manually. Therefore, must be automated if it’s the choice for welding stainless steel.
The processes that are mentioned above are the most common processes used to weld stainless steel. There are a few less popular processes too for welding stainless steel. These processes include:
- Electron beam welding
- Friction stir welding
- Plasma arc welding
- Resistance welding
- Shielded metal arc
Along with these, there are various other welding processes you can use to weld stainless steel. Whenever you are welding, be sure that you take the right protective measures such as safety gear and a welding helmet. To see the variety of excellent welding helmets, check out Welding Corner.